The demand for broadband access and multimedia services is ever increasing with various applications in business, education and entertainment. This has been recognized by political authorities such as the European Commission through its Digital Agenda, which aims among others at guaranteeing a minimum bitrate across Europe. In order to implement this directive over sparsely populated areas, satellite interactive services constitute the only financially feasible solution. More importantly, satellite services can also provide broadband services to maritime and aeronautical markets, promoting thus ubiquitous internet access.However, the available frequency resources are becoming scarce due to the spectrum segmentation and the dedicated frequency allocation of the standardized wireless systems. This phenomenon results in long conflicts during the World Radiocommunication Conference which takes place every four years in order to regulate and reallocate spectrum. In this direction, it is crucial to find wireless communication strategies which enable the spectral coexistence of two satellite or satellite/terrestrial services on a primary/secondary or coprimary basis. Nevertheless, by enabling the spectral coexistence, incidents of intentional or non-intentional interference may appear more frequently. Interferers can induce large financial losses to satellite operators which might be unable to respect their Service Level Agreements (SLAs). In this context, it is imperative to implement innovative satellite systems which can mitigate harmful interference in coexistence scenarios. The proposed project SeMIGod stands for “SpEctrum Management and Interference mitiGation in cOgnitive raDio satellite networks”. It is structured around enabling coexistence of 1) two satellite services or 2) a satellite and a terrestrial service on a I) primary/secondary or II) coprimary basis. The aforementioned objective shall be addressed through the exploitation of cognitive communication techniques  which can be categorized in interweave, underlay and overlay. Interweave essentially refers to opportunistic transmission in temporarily unused carriers, while underlay allows transmission in occupied carriers as long as predefined interference constrains are respected. Overlay relies on advanced transmission schemes (e.g. relaying) which can serve the secondary user while simultaneously helping the primary transmission. In this direction, two main scenarios will be investigated: a) Hybrid Satellite Cognitive Systems and b) Dual Satellite Cognitive Systems. Cognitive satellite systems are based on hybrid networks which combine a ground and a satellite component operating over the same frequency bandwidth. Based on cognitive overlay and underlay techniques, both ground and satellite components can communicate simultaneously with the users without the need of orthogonalization (Frequency Division), minimizing the need of purchasing expensive bandwidth. In addition, this concept can lead to the integration of satellite and terrestrial services in order to support ubiquitous indoors and outdoors coverage. The focus of this project will be on enabling the coexistence of a) Fixed Satellite Services (FSS) and Fixed Services (FS) in suitable segments of Ku/Ka-band and b) satellite and terrestrial services in suitable segments of C-band. On the other hand, dual satellite cognitive systems aim at enabling the coexistence between two satellite services. The considered scenarios in this category are a) two multibeam satellites with different coverage patterns in Ka-band and b) coexistence of Non-Geostationary Satellite Orbit (NGSO) FSS systems and Geostationary Satellite Orbit (GSO) systems in Ka-band.